A study of the chloride permeability of rigid concrete bridge deck overlays was conducted during the 1987 construction season. A total of thirteen latex-modified concrete (LMC) overlays, ten superplasticised dense concrete (SDC) overlays, and two condensed silica fume concrete (CSFC) overlays, were investigated. Concretes were tested both by the rapid chloride permeability test and by 90-day chloride ponding. Results of this study indicate that, of the three materials tested, CSFC is the most impermeable to chloride ions. Following CSFC, in order of increasing permeability, are LMC and SDC. Although all materials show a decrease in permeability with age, chloride ions slowly penetrate these materials and can build up to substantial levels over long periods of time. For newly constructed overlays, there was a good correlation between results of the rapid chloride permeability and 90-day ponding tests.
Samenvatting